1. Field of Invention
A scroll compressor has two scrolls made up of spiral wraps which are integral with, or mounted to, corresponding plates. In assembly, the spiral wraps are inter-fitted such that one wrap is rotationally displaced 180.degree. with respect to the other. The wraps and the plates coact to define a plurality of symmetrical lunettes. At the tips of the lunettes a seal is established between the flanks of the two wraps. The flanks may be in actual line contact or may have a small clearance which is typically sealed by oil. At the top and bottom of each lunette there is an axial seal between the tip of the wrap of one scroll and the opposing plate of the other scroll and they may be in actual contact, may employ tip seals and may even allow for a differential thermal expansion across the scrolls. One scroll is fixed and the other scroll is driven in an orbiting motion relative to the fixed scroll. The compression process begins at the periphery of the wraps and proceeds inwardly to a centrally located common discharge port. The tips of the lunettes move along the walls of the wraps during the compression process while the tips of the wraps of the fixed and orbiting scrolls relatively move across the face of the opposing plate in an orbiting motion. In a conventional wrap configuration, as many as three symmetrical pairs of lunettes can exist at any time. Because the lunettes decrease in volume as they move from suction to discharge, there is a pressure differential across the flank seals and tip seals which creates a tendency for leakage.
2. Description of the Prior Art
A radial compliance mechanism has been used to provide the flank seals by allowing controlled radial movement of the orbiting scroll with respect to the fixed scroll by varying the eccentricity. One type of device used for this purpose is an eccentric bushing. This type of device is activated by gas and/or centrifugal forces and provides a radial sealing force between the wraps thereby reducing radial clearances and leakage as well as minimizing the effects of manufacturing tolerances.